This invention relates to cheese block forming towers and in particular an installation involving several such towers (a multi-tower installation) fed from a common supply.
Cheese block forming towers are known and consist primarily of a tower with an output severing device and associated block chamber at the base. Cheese curd is introduced into the top of a perforated whey extraction column within the tower. The curd at the bottom of the column is compressed by the weight of the curd thereabove causing the whey to be expressed through the perforations. A vacuum is also created in the tower to remove air from the whey and assist in the extraction of the whey. Individual blocks are severed from the bottom of the column of curd by the severing device that in some instances also further compresses the block.
Apparatus and methods of this type are described in various patents including UK Patents 1187964 and 1542844 and also U.S. Pat. Nos. 3,982,480 and 4,539,902. A critical function of these towers is to produce cheese blocks to a constant xe2x80x9cstandardxe2x80x9d weight. Owing to the variance in the components of curd this can mean the processing time to achieve a block of a required weight varies during production. The throughput of these traditional towers has been published at nominally one xe2x80x9cstandardxe2x80x9d 20 kg block of cheese curd every 1.5 minutes. In our NZ Patent Application 265118 we disclose a tower having a column height extended beyond that of the columns of traditional lowers. The throughtput of our extended column tower is nominally one xe2x80x9cstandardxe2x80x9d 20 kg block of cheese curd every minute. This is a significant increase over the traditional towers.
There remain various limitations to throughput of all these known towers particularly, as is normal, with multi-tower installations fed from a common supply of curd. In part this comes about owing to the inability of multi-tower installations to maintain a balance between the feed to the individual towers and the rate and sequence cheese blocks are discharged from the towers. On the one hand, the throughput capabilities of the towers can exceed the capability of the rest of a plant to provide sufficient input to the towers. Further, the throughput of one tower may be greater than one or more of the other towers of a multi-tower installation. This can also cause a fluctuating input to one or more of the towers and one or more of the towers may be starved of supply. On the other hand, if delay occurs in one or more of the towers from malfunction, excess processing time or otherwise the input to the towers may cause overloading necessitating or causing a shut down in one or more sections of the plant. The effect of this imbalance can be unacceptable weight variations in the blocks formed by a tower. This can necessitate inefficient downstream processing to xe2x80x9cstandardisexe2x80x9d the blocks. Unacceptable product finish effects can also result. For example, cooling of the top of a curd column owing to excessive exposure to air in the absence of fresh curd arriving can cause excessive processing time and consistency problems.
An object of this invention is to provide a cheese block forming tower suitable for use in multi-tower installations that it is envisaged will provide an improved through-put over known towers while maintaining the appropriate integrity of cheese blocks produced. It is also envisaged that this invention will be suitable for use in combination with at least our other two inventions being concurrently filed. These claim priority from New Zealand patent application Nos. 333114 and Australian patent application PP 7743/98. A further object is to provide a useful choice over known apparatus.
According to one aspect of this invention there is provided a cheese block forming tower incorporating a whey supply inlet to a whey drainage column with a severing device having a cheese block support platform as the output thereof characterised in that control means are provided to substantially continuously monitor both the output of the severing device and the curd to cheese conversion pressing time of the tower to adjust at required intervals the output of the tower block severing device and simultaneously or as otherwise required also activate a charge of curd from the supply to the tower as to achieve a substantially uniform supply of curd to the tower.
According to a second aspect of this invention there is provided a cheese block forming tower as described in the preceding paragraph wherein the controller also adjusts the curd to cheese processing time dependent upon the frequency the supply of a recharge of curd occurs and controls the operation of the block platform to adjust the output of the tower.
According to a third aspect of this invention there is provided a cheese block forming tower installation comprising at least two block forming towers each incorporating a whey supply inlet to a whey drainage column with a severing device having a cheese block support platform as the output thereof, the towers being coupled to common curd supply characterised in that each tower has a pair of sensors mounted in spaced apart relationship one above the other in the column thereof to provide the controller with data on the block processing time of each tower, the controller also monitoring and controlling the operation of the severing device of each tower whereby the controller by substantially continuously monitoring both the output of the severing device and the curd to cheese conversion pressing time of each tower can adjust at required intervals the output of each tower block severing device and simultaneously or as otherwise required also activate a charge of curd from the supply to a tower as to achieve a substantially uniform supply of curd to each tower.
According to a fourth aspect of this invention there is provided a cheese block forming tower installation as described in the preceding paragraph wherein the controller also co-relates the output of the towers and adjusts the processing time of each to enable the controller to establish a forward sequence for the towers the controller determines to be next in line to discharge blocks and to so activate the severing devices of those towers.